The aim of our study is to clarify our understanding of the nature and to document the course of panic disorder in children. This revised study will expand an earlier one (NIMH Small Grant) in the obvious sense that it will consider a far larger sample of children and adolescents with panic attacks (PA) and panic disorder (PD) assessed with a structured interview and current diagnostic criteria. During the time of the Small Grant we were successful in recruiting and studying 72 children, ages 7 to 18, with PA or PD. From the 72 children, at least 60 children (40 with ad diagnosis of PD, 20 with a diagnosis of PA) will be available for this new study. These children will be studied more intensively during this grant and, in addition, we will increase the sample size of children with PA and PD to 100 through continued recruitment. By the start of this grant at least 60 depressed non-panic children, ages 7 to 18, will be available as a control group for this study. A second control group of 60 never-psychiatrically- ill children will be recruited from the same community. This new study is designed to obtain more focused data on 100 children, ages 7 to 18, with DSM-IIIR PA or PD. Specifically, we will determine; 1) the natural history of PA and PD, stability of diagnosis over time, social impairment and development of comorbid disorders in children with PA or PD as compared to depressed non-panic children and normal children; 2) the response of adolescents with PD-no current major depression to biological challenges (CO2 inhalation and clonidine) as compared to the two control groups. To accomplish these aims, we will: 1) initiate a 3 year longitudinal follow- up study of 100 children with PA and PD and compare to similar follow-up data on two matched control groups; 60 depressed non-panic children and 60 never-psychiatrically-ill children; 2) perform biological challenge studies in 28 adolescents with current PD-no current major depression and compare to data on: 28 adolescents with major depression-no-history of PD and 28 never-psychiatrically-ill adolescents at low risk for the development of psychiatric disorder by virtue of the absence of psychiatric disorders in their parents as determined by a family history screen. The following hypothesis are the basis of this study: 1) children with PA, particularly those who come from families with panic, will eventually develop PD; 2) children with PD (especially those who come from families with panic) will have stability of PD over time and will have impairment in school and social functioning 3) adolescents with PD will exhibit the biological abnormalities found in adults with PD (i.e. blunted human growth hormone in response to clonidine challenge and increased panic response to CO2 inhalation). This study will be the first to longitudinally study children with PA and PD and to conduct biological studies. The information generated on childhood PD can provide the rationale for early treatment and, hopefully, prevention of the full-blown disorders and the serious impairment in brings.